What is the role of serum mature tryptase measurement in the diagnosis of anaphylaxis?

Updated: May 16, 2018
  • Author: S Shahzad Mustafa, MD; Chief Editor: Michael A Kaliner, MD  more...
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Serum mature tryptase (previously called beta-tryptase) levels peak 60-90 minutes after the start of an episode and may persist for as long as 5 hours. The estimated positive predictive value of tryptase elevations in 259 subjects with anesthesia-associated anaphylaxis is 92.6%, and the estimated negative predictive value of normal tryptase levels is 54.3%. Serial tryptase measurements might improve diagnostic sensitivity, but further investigation is needed.

Basal levels of total and mature tryptase between episodes of anaphylaxis can be helpful to rule out systemic mastocytosis. Patients with mastocytosis constitutively produce large quantities of alpha-tryptase, while individuals with anaphylaxis from other causes have normal levels of alpha-tryptase at baseline between episodes of anaphylaxis. During anaphylaxis, a ratio of total tryptase (alpha + mature) to mature tryptase of 20 or greater is consistent with mastocytosis, whereas a ratio of 10 or less suggests anaphylaxis of another etiology.

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